Just to be clear, when you say "without the need for the GUI", more accurately that's "without a GUI" (w/o Presentation Manager). So you're using OS/2 in an 80x25 console screen, what would appear to be a very good DOS box.
It exists in that interesting but obsolete interstitial space alongside BeOS of very well done single user OS.
Btw, I'd love to know where this idea about no assembler programs on OS/2 came from. There was no problem at all with using MASM, with CodeView to debug on a second screen.
It’s certainly a misunderstanding - nothing prevents someone from writing assembly. Could also be a lack of official documentation on how to make the API calls from assembly. Another possible source is that you can’t access the hardware directly in OS/2, which was more closely associated with low-level programming.
Just as a brief explanation: this was in the late 80's. I was using a device called an imaging photon detector to detect individual photo events. This was the back end of an early electronic camera running at about ISO 1G. Not a digital camera - the photo events were recorded as analogue xy coordinates, with a resolution of about 400x400 and a photon rate of about 100k/s (not an exact figure - as the rate increased, you lost an increasing number of events due to clash. I had a load of wire-wrap to rearrange the bits before they were presented to the computer (bit-bashing on the 80386/33 wasn't fast enough), then the xy coordinated were presented to some sort of PIO. In some cases I wanted to take video, hence the hardware clock, since the nearest thing available on the PC only ran at something like 13.3Hz and was used for polling the mouse. There was no GUI available at the time, so I built my own.
I don't remember a huge amount of detail, and the source is on 5¼" floppy, but as I remember it none of this was difficult for a very amateur self-taught C/asm programmer. The only significant problem was working out that the OS/2 1.0 documentation of the mouse system lied (it didn't have the display capability claimed, and attempting to use it shut down mouse polling), and third party manuals just copied the lies without testing. That was easy enough to work out, and building a couple of threads to display the mouse cursor was easy.
I think I'm going to see if I can find a service which will read the disk - it would be nice to have the code, though I remember there was a lot of stuff ♯defined out where I would have used SCCS once I had it available - hence it was a bit messy.
One little vexation was that although I had a vast 64MB hard disk, and a 1GB (bites tip of little finger) optical WORM drive, I had to reboot in to MS/DOS to use the WORM drive (no OS/2 drivers) and because one of the operating systems couldn't handle more than 32MB disk size, I had to partition the hard disk.
300 Megabytes!!!
I had all my source code on it, archives, utilities, compilers, the whole shebang!
[1] http://www.bitsavers.org/pdf/microSolutions/MicroSolutions_P...
Oh the screen would go to snow often, and sidekick would bring it right back.
How well did OS/2 handle the text modes for VGA?
I regularly ran in 50-line VGA mode with zero problems. One could session-switch between full-screen OS/2 TUI programs (that were genuinely operating the hardware in VGA text mode, not simulating it with the hardware itself being used in graphics mode as became the norm with other operating systems much later and which OS/2 itself never got around to) and the Presentation Manager desktop.
I even had a handy LINES 50 command that wrapped the VIO mode change function, that I gave to the world as one of many utilities accompanying my 32-bit CMD, and which in 32-bit form was layered on top of a debugged clean room reimplementation of IBM's never-properly-shipped-outwith-the-Developers'-Toolkit 32-bit version of the VIO API.
You can still download it from Hobbes, today.
* https://hobbesarchive.com/?detail=/pub/os2/util/shell/32-bit...